In many airports, especially small airports, some passengers are required to walk outside between a terminal gate and an aircraft. Passengers and airport personnel must be kept at a sufficient distance from any aircraft having a gas turbine engine in operation. Even if they are not in the immediate vicinity of aircrafts, passengers and airport personnel must keep away from them due to the noise and the wake created by an operating engine. This may increase the interval between an arrival and a departure, which can be a significant drawback, especially in the case of aircrafts whose operations involve numerous short stops. Also, crowed airports may require aircrafts to run engines at idle or at low speeds for a long time between a terminal gate and the runway, or vice-versa. Running at least one engine is required to taxi the aircraft and it must be maintained in operation until the aircraft reaches the runway or its gate at the service area, depending on the case. Since fuel is burned during the operation of the engine, any delay while taxiing an aircraft increases its operating costs.